Qualidade da água de abastecimento urbano da Região de Marudá, município de Marapanim, Zona Costeira do Estado do Pará

Abstract

The village of Marudá has a population of 2417 inhabitants, whose main source of water supply is the underground aquifers. The present work concerns the determination of physical, physical-chemical, chemical and bacteriological parameters of the urban water supply for the population of Marudá, in order to characterize its water for human consumption. The field work was performed during the rainy season from April 25 to 26, 2004. Ten sampling points were established, including household taps (COSANPA water), Amazon wells (from the households themselves) and surface waters (Marudá river). The methods used are based on Standard Methods (1998). The results obtained will be framed in the ordinance 518/2004 of the Ministry of Health. The dissolved oxygen content showed indices varying from 4.26mgIL to 7.84mgIL. The COD values of the analyzed points showed an amount of oxidizable organic matter, with the highest concentration in point P3 (well water) of 85 mgIL. Regarding the ammoniacal nitrogen contents, they ranged from 0.28mgIL to 0.98mgIL, which are in conformity with the acceptance standards for human consumption. Among the cations analyzed (Na, Ke Ca), the dominant element was Ca in the groundwater. It is important to emphasize the normal concentrations of Na, which rules out the possibility of underground contact of the groundwater aquifers with the saline water of the coastal region studied. Iron contents were detected in the well waters (P4 and P7) and in the public supply system (T2 and T9), according to the potability standards, whose maximum allowed value is 0.3 mg/L. The temperature of the underground water of this region reflected its climatic conditions, its values "ín situ" varied between 24, °C to 28, °C. The pH values were moderately acid, with exception of the points T6 (tap) and R10 (Marudá River) that obtained alkaline pH. Groundwater salinity was zero. Total and fecal coliforms were detected only in point P3 (well water), which presented a concentration of 1100 NMP/100 mL for total and fecal coliforms, probably due to the "insitu" sanitation system used in the Municipality - septic tanks. Such verifications determine the non-compliance with the ordinance no 518/2004 of point P3.